Will the dbspace change when the value in the row changes under FRAGMENT BY EXPRESSION? (Informix DB)

Question

Unfortunately, I have not found an explanation for this situation in the documentation.

In particular, I created a table and fragmented it "FRAGMENT BY EXPRESSION" by the "value" field. In the fragmentation condition, I wrote:

value <  100 IN dbspace_1,
value >= 100 IN dbspace_2.

For example, "value" in the row is 85, so the row is located in dbspace_1. If I update the value to 110, will this row move to dbspace_2?

Answer 1

Yes. If it didn't it would invalidate the fragment expression schema. You can verify this yourself if you have a test instance by doing the update and then looking at the onlog output. You should see a delete from the partition in dbspace1 followed by an insert into the partition in dbspace 2 in a single transaction (this would be easiest to see on an unused system where you could switch to a completely unused logical log to help easily spot the transaction used for the update statement).